Interpretive Summary: We have developed a method that uses a food-grade bacterial enzyme to modify carbohydrates from biomass and convert them to new carbohydrates with potential applications in food and feed. Cellobiose is a carbohydrate that arises from the breakdown of cellulose from wood, straw, and most other plant biomass. This new process modifies cellobiose to give novel carbohydrate that show promise as prebiotics, which enhance the growth of beneficial bacteria. The carbohydrates derived from cellobiose showed similar prebiotic activity to those derived from maltose, which is made from starch. Thus, woody biomass may be substituted for starch as a source of prebiotic carbohydrates. This process could be used in the production of valuable food and feed additives from cheap biomass.

Technical Abstract:
The selective fermentation by human gut bacteria of gluco-oligosaccharides obtained from the reaction between the glucosyl group of sucrose and cellobiose, catalyzed by dextransucrases from Leuconostoc mesenteroides, has been evaluated. Oligosaccharides were fractionated according to their molecular weight and their effect on the growth of different bacterial groups was studied. In order to determine the structure-function relationship (position and configuration of glycosidic linkages), their properties were compared to those of DSR maltose acceptor products and of recognised prebiotic carbohydrates (FOS). Cellobiose acceptor products showed bifidogenic properties similar to those of FOS. No significant differences related to molecular weight or isomeric composition were detected. Gluco-oligosaccharides containing a-(1'2) linkages showed a selective growth of Bifidobacteria, whereas no significant differences were found with oligosaccharides containing a-(1'4) and a-(1'6) linkages.